The Clinical trial (CT) will evaluate the benefits and risks of Hormone Replacement Therapy (HRT), Dietary Modification (DM), and supplementation with calcium/vitamin D (CaD) on the overall health of postmenopausal women. Health will be assessed on the basis of quality of life measurements, cause-specific morbidity and mortality, and total mortality. It is hypothesized that estrogen replacement therapy (ERT) and combined progestin and estrogen replacement therapy (PERT) will reduce the risk of coronary heart disease (CHD) and of osteoporosis-related fractures. Women who are post-hysterectomy will be randomized to ERT or placebo, while women with a uterus will be randomized to PERT or placebo. The incidence of endometrial cancer and breast cancer will be monitored during and after the trial.